Fast bowler Dale Steyn ripped through New Zealand's batting as South Africa took control on the second day of the first Test at the Wanderers Stadium on Friday, then predicted New Zealand would have more trouble in the second innings.

After Steyn destroyed the New Zealand first innings, Hashim Amla (85 not out) and Jacques Kallis (76 not out) shared an unbeaten 159-run stand as South Africa reached 179 for two at the close in their second innings, an overall lead of 287.

Steyn took career-best figures of five for 34 as New Zealand crashed to 118 all out. Makhaya Ntini took three for 47 and Kallis two for 11.

"It will get more difficult (for batsmen) as the game goes on," said Steyn. Uneven bounce was a big factor. "The guys don't know whether to duck or not, or whether to go forward or back."

Steyn said the South Africans realised there was most help for bowlers in the morning and said they had been determined to strike early. They did so effectively, with New Zealand scoring only 56 runs and losing five wickets before lunch.

With the sun shining after an overcast first day, New Zealand must have been confident of overhauling South Africa's disappointing first innings total of 226.

But even though there was no help from the overhead conditions, the South African fast bowlers kept their opponents under constant pressure.

Former captain Stephen Fleming made 40 and the next best score in a dismal batting performance was new cap Ross Taylor's 15.

Fleming was struck on the right forearm by Steyn and did not field during the afternoon. Coach John Bracewell said he had gone for precautionary X-rays which had revealed there was only bruising.

Bracewell remained upbeat about New Zealand's chances. Unlike Steyn, he thought the pitch had flattened out and become easier to bat on.

But he admitted that a missed chance, when Brendon McCullum dropped Amla on two off Shane Bond, had been a costly error.

"The ball was hard and new and we were trying to get momentum. It cost us a lot," he said.

Bracewell said it was disappointing not to have capitalised on the first day's bowling performance. "To bowl a side out for 226 on the first day and then not take advantage is a missed opportunity," he said.

New Zealand, resuming at 41 for two, quickly lost nightwatchman Shane Bond, bowled by a Steyn yorker, before Ntini claimed the crucial wicket of Fleming, who was well caught by AB de Villiers diving to his left at third slip.

Scott Styris and Taylor eked out 19 runs in 10 overs in New Zealand's best partnership of the day before the clatter of wickets resumed.

Steyn's figures bettered his previous best of five for 47 against the same opponents at Centurion two seasons ago. It was his fourth five-wicket haul in 14 Tests.

Batsmen continued to struggle when South Africa started their second innings, with openers Herschelle Gibbs and captain Graeme Smith both out cheaply.

But Amla and Kallis dug in with careful batting to sap the energy from the New Zealand bowlers, who did not bowl with as much venom as they showed on the first day.

By the close, Amla and Kallis had batted together for 205 minutes. Amla faced 230 balls and hit 13 boundaries while Kallis hit 12 fours off 122 deliveries.